NeilBrown
8e0e99ba64
md/raid5: disable 'DISCARD' by default due to safety concerns. ...
It has come to my attention (thanks Martin) that 'discard_zeroes_data'
is only a hint. Some devices in some cases don't do what it
says on the label.
The use of DISCARD in RAID5 depends on reads from discarded regions
being predictably zero. If a write to a previously discarded region
performs a read-modify-write cycle it assumes that the parity block
was consistent with the data blocks. If all were zero, this would
be the case. If some are and some aren't this would not be the case.
This could lead to data corruption after a device failure when
data needs to be reconstructed from the parity.
As we cannot trust 'discard_zeroes_data', ignore it by default
and so disallow DISCARD on all raid4/5/6 arrays.
As many devices are trustworthy, and as there are benefits to using
DISCARD, add a module parameter to over-ride this caution and cause
DISCARD to work if discard_zeroes_data is set.
If a site want to enable DISCARD on some arrays but not on others they
should select DISCARD support at the filesystem level, and set the
raid456 module parameter.
raid456.devices_handle_discard_safely=Y
As this is a data-safety issue, I believe this patch is suitable for
-stable.
DISCARD support for RAID456 was added in 3.7
Cc: Shaohua Li <shli@kernel.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Heinz Mauelshagen <heinzm@redhat.com>
Cc: stable@vger.kernel.org (3.7+)
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Fixes: 620125f2bf
2014-10-02 13:45:00 +10:00
bcache: Drop unneeded blk_sync_queue() calls
2014-08-04 15:23:04 -07:00
dm transaction manager: fix corruption due to non-atomic transaction commit
2014-03-27 16:56:23 -04:00
md/bitmap: remove confusing code from filemap_get_page.
2014-05-29 16:59:47 +10:00
kernfs: s/sysfs_dirent/kernfs_node/ and rename its friends accordingly
2013-12-11 15:28:36 -08:00
dm bio prison: implement per bucket locking in the dm_bio_prison hash table
2014-06-11 16:48:54 -04:00
dm thin: return ENOSPC instead of EIO when error_if_no_space enabled
2014-06-03 13:44:08 -04:00
dm: Refactor for new bio cloning/splitting
2013-11-23 22:33:55 -08:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-08-04 16:23:30 -07:00
dm snapshot: use dm-bufio prefetch
2014-01-14 23:23:03 -05:00
dm sysfs: fix a module unload race
2014-01-14 23:23:04 -05:00
dm cache: remove remainder of distinct discard block size
2014-03-27 16:56:23 -04:00
dm cache metadata: use dm-space-map-metadata.h defined size limits
2014-08-01 12:30:33 -04:00
dm cache metadata: use dm-space-map-metadata.h defined size limits
2014-08-01 12:30:33 -04:00
dm cache: add remove_cblock method to policy interface
2013-11-11 11:37:50 -05:00
dm cache mq: fix memory allocation failure for large cache devices
2014-02-28 12:18:29 -05:00
dm cache: add policy name to status output
2014-01-16 13:44:11 -05:00
dm cache: add policy name to status output
2014-01-16 13:44:11 -05:00
dm cache: fix race causing dirty blocks to be marked as clean
2014-09-10 11:20:47 -04:00
dm crypt: fix access beyond the end of allocated space
2014-08-28 14:24:09 -04:00
Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block
2014-01-30 11:19:05 -08:00
dm era: check for a non-NULL metadata object before closing it
2014-06-03 13:44:08 -04:00
block: Abstract out bvec iterator
2013-11-23 22:33:47 -08:00
dm io: simplify dec_count and sync_io
2014-08-01 12:30:30 -04:00
dm: allow remove to be deferred
2013-11-09 18:20:22 -05:00
dm: stop using WQ_NON_REENTRANT
2013-08-23 09:02:13 -04:00
block: Abstract out bvec iterator
2013-11-23 22:33:47 -08:00
dm log userspace: allow mark requests to piggyback on flush requests
2014-01-21 23:46:27 -05:00
connector: add portid to unicast in addition to broadcasting
2014-02-07 15:40:17 -08:00
dm mpath: eliminate pg_ready() wrapper
2014-08-01 12:30:31 -04:00
dm raid1: fix immutable biovec related BUG when retrying read bio
2014-02-18 10:48:57 -05:00
block: Abstract out bvec iterator
2013-11-23 22:33:47 -08:00
dm snapshot: fix metadata corruption
2014-03-03 17:58:13 -05:00
sched: Remove proliferation of wait_on_bit() action functions
2014-07-16 15:10:39 +02:00
dm stats: initialize read-only module parameter
2013-12-10 19:13:21 -05:00
dm: add statistics support
2013-09-05 20:46:06 -04:00
block: Abstract out bvec iterator
2013-11-23 22:33:47 -08:00
dm switch: efficiently support repetitive patterns
2014-08-01 12:30:37 -04:00
dm sysfs: fix a module unload race
2014-01-14 23:23:04 -05:00
dm table: propagate QUEUE_FLAG_NO_SG_MERGE
2014-08-10 20:54:49 -04:00
dm: allow error target to replace bio-based and request-based targets
2013-09-05 20:46:05 -04:00
dm thin metadata: do not allow the data block size to change
2014-07-15 14:05:26 -04:00
dm thin: ensure user takes action to validate data and metadata consistency
2014-03-05 15:25:35 -05:00
dm thin: set minimum_io_size to pool's data block size
2014-08-01 12:30:35 -04:00
dm verity: fix biovecs hash calculation regression
2014-04-15 12:19:24 -04:00
dm crypt, dm zero: update author name following legal name change
2014-07-10 16:44:14 -04:00
dm: allocate a special workqueue for deferred device removal
2014-07-10 16:44:13 -04:00
dm table: make dm_table_supports_discards static
2014-08-01 12:30:34 -04:00
block: Abstract out bvec iterator
2013-11-23 22:33:47 -08:00
dm: add era target
2014-03-27 16:56:23 -04:00
block: Introduce new bio_split()
2013-11-23 22:33:57 -08:00
dm: add era target
2014-03-27 16:56:23 -04:00
md: don't allow bitmap file to be added to raid0/linear.
2014-08-08 15:43:20 +10:00
md/bitmap: don't abuse i_writecount for bitmap files.
2014-04-09 12:26:59 +10:00
block: Abstract out bvec iterator
2013-11-23 22:33:47 -08:00
md/raid0: check for bitmap compatability when changing raid levels.
2014-08-08 15:33:17 +10:00
md/raid1: fix_read_error should act on all non-faulty devices.
2014-09-22 11:26:01 +10:00
raid1: Rewrite the implementation of iobarrier.
2013-11-19 15:19:18 +11:00
md/raid5: disable 'DISCARD' by default due to safety concerns.
2014-10-02 13:45:00 +10:00
raid5: add an option to avoid copy data from bio to stripe cache
2014-05-29 16:59:47 +10:00
md/raid10: always initialise ->state on newly allocated r10_bio
2014-08-19 17:20:27 +10:00
8e0e99ba64